Generally, there is a need to heat specimens to high temperatures for testing and analytical purposes, among other possible reasons. For instance, during a strain controlled fatigue test, a specimen can be heated to temperatures at or exceeding 2400° F. by a high temperature furnace. In some cases, such as when testing a specimen formed of a Ceramic Matrix Composite (CMC) material, it is desirable to heat the CMC specimen to temperatures at or exceeding 2700° F. It may likewise be desirable to heat other materials having high temperature capability to high temperatures.
Conventional high temperature furnaces used to heat such specimens are typically capable of reaching high temperatures. However, such conventional high temperature furnaces tend to fail when operated at high temperatures during prolonged operating periods, such as e.g., when heating a CMC specimen for the duration of a run-out strain controlled fatigue test. In addition, such conventional high temperature furnaces typically include one or more heating elements that provide a single heating zone for heating the specimen. Thus, there is no opportunity to test how the specimen will react when subjected to multiple heating zones. Furthermore, the single heating zone provided by conventional high temperatures furnaces may not produce an acceptable temperature gradient profile of the test specimen that is within testing specifications.
Moreover, in an attempt to maintain the set point temperature within the heating chamber of such conventional furnaces, large amounts of current are passed through the heating elements, which negatively impacts the energy efficiency of the furnace and disrupts testing instrumentation. Additionally, the heating elements of conventional furnaces are oriented and configured in such a way (e.g., U-shaped heating elements) that they effectively increase the size of the furnace, making the high temperature furnace assembly bulky and more costly.
Therefore, there is a need for improved high temperature furnaces that address at least some of these noted challenges.